There is a website for the Burning Man event but I don't recall what it is at the moment. It has a frequency page on it that lists the amateur radio frequencies being used as well as the frequencies used by the event "organizers" themselves. If I was attending the event I would program one bank with the NIFC tacticals at least and since there should be room, I would program in the NIFC command and logistics also. The law enforcement at the event includes both Bureau of Land Management and Forest Service law enforcement offers (LEO's) at the least (LEO's I worked with in the U.S. Forest Service were detailed to Burning Man every year) and LEO's from the U.S. Fish and Wildlife Service as well as the National Park Service might be there as well. This in addition to the county and state officers that would be working the event and the roads near the event. Another bank could be devoted to the FRS/GMRS frequencies as I'm sure those would be active, but of marginal interest as a lot of personal type communications (Can you get ice out of the cooler and meet me by the big jewelery tent?) would be going on.
In addition I believe the event has a business frequency or two licensed to them. I think they are national itinerant business frequency(s) such as 151.625.
The NIFC frequencies are listed at:
http://wiki.radioreference.com/index.php/National_Incident_Radio_Support_Cache
If you have time, I would search the full gamut of frequencies such as the Maritime frequencies and business frequencies in the VHF and UHF (450 + MHz) as some folks bring their business band radios from their businesses where their use if authorized, to large events like these where they are not. The marine radios commonly get used far from any navigable waters as subtitle family radios so a quick scan of those can sometimes find inter sting traffic.